New Quaternary mammals support regional endemism in western Hispaniola

Abstract

Analysis of largely unstudied fossil collections recovered from caves and sinkholes from western Hispaniola has resulted in the recognition of a new capromyine rodent (Zagoutomys woodsi, gen. et sp. nov.) and a new solenodontid (Solenodon ottenwalderi sp. nov.). Fossils of Z. woodsi show that it differs from other capromyine rodents in having a mandible with a relatively thin and elongated symphysis, a relatively long diastema between the lower incisor and dp4, a more procumbent incisor, and a more anteriorly positioned masseteric crest. Results from a phylogenetic analysis suggest that Z. woodsi is closely related to the Plagiodontia clade, which includes living P. aedium and two extinct species. While fossils referred to Z. woodsi are rare (n = 18) among the thousands of rodent specimens recovered from the study sites, their geographic distribution suggests it was present across western Hispaniola. In contrast, fossils of S. ottenwalderi are relatively abundant in several localities but restricted to the western portion of the Tiburon Peninsula, like other regionally endemic extinct taxa, including the platyrrhine primate Insulacebus toussaintiana and the capromyine rodent Rhizoplagiodontia lemkei. Fossils of S. ottenwalderi show that it was notably smaller than other species of Solenodontidae, reducing the body size gap between this genus and Nesophontes. A phylogenetic analysis suggests that S. ottenwalderi is sister to the extinct species S. marcanoi and both are sister to extant S. paradoxus, forming a monophyletic clade endemic to Hispaniola. Morphological and body size differences of these two new mammals with respect to their sister taxa might suggest niche differentiation with segregation of available resources in these past island ecosystems.